Chapter 22
java.awt.image Reference

PixelGrabber

Name

PixelGrabber

[Graphic: Figure from the text]

Description

The PixelGrabber class is an ImageConsumer that captures the pixels from an image and saves them in an array.

Class Definition

public class java.awt.image.PixelGrabber
    extends java.lang.Object 
    implements java.awt.image.ImageConsumer {
  // Constructors
  public PixelGrabber (Image img, int x, int y, int w, int h, 
      boolean forceRGB); 
  public PixelGrabber (Image image, int x, int y, int width, 
      int height, int[] pixels, int offset, int scansize);
  public PixelGrabber (ImageProducer ip, int x, int y, int width, 
      int height, int[] pixels, int offset, int scansize);
  // Instance Methods
  public synchronized void abortGrabbing(); 
  public synchronized ColorModel getColorModel(); 
  public synchronized int getHeight(); 
  public synchronized Object getPixels(); 
  public synchronized int getStatus(); 
  public synchronized int getWidth(); 
  public boolean grabPixels() throws InterruptedException;
  public synchronized boolean grabPixels (long ms) 
      throws InterruptedException;
  public synchronized void imageComplete (int status);
  public void setColorModel (ColorModel model);
  public void setDimensions (int width, int height);
  public void setHints (int hints);
  public void setPixels (int x, int y, int width, int height, 
      ColorModel model, byte[] pixels, int offset, int scansize);
  public void setPixels (int x, int y, int width, int height, 
      ColorModel model, int[] pixels, int offset, int scansize);
  public void setProperties (Hashtable properties);
  public synchronized void startGrabbing(); 
  public synchronized int status(); 
}

Constructors

PixelGrabber

public PixelGrabber (Image img, int x, int y, int w, int h, boolean forceRGB)

Parameters

img

Image to use as source of pixel data.

x

x-coordinate of top-left corner of pixel data.

y

y-coordinate of top-left corner of pixel data.

w

Width of pixel data.

h

Height of pixel data.

forceRGB

true to force the use of the RGB color model; false otherwise.

Description

Constructs a PixelGrabber instance to grab the specified area of the image.

public PixelGrabber (Image image, int x, int y, int width, int height, int[] pixels, int offset, int scansize)

Parameters

image

Image to use as source of pixel data.

x

x-coordinate of top-left corner of pixel data.

y

y-coordinate of top-left corner of pixel data.

width

Width of pixel data.

height

Height of pixel data.

pixels

Where to store pixel data when grabPixels() called.

offset

Offset from beginning of each line in pixels array.

scansize

Size of each line of data in pixels array.

Description

Constructs a PixelGrabber instance to grab the specified area of the image and store the pixel data from this area in the array pixels[].

public PixelGrabber (ImageProducer ip, int x, int y, int width, int height, int[] pixels, int offset, int scansize)

Parameters

ip

ImageProducer to use as source of pixel data.

x

x-coordinate of top-left corner of pixel data.

y

y-coordinate of top-left corner of pixel data.

width

Width of pixel data.

height

Height of pixel data.

pixels

Where to store pixel data when grabPixels() called.

offset

Offset from beginning of each line in pixels array.

scansize

Size of each line of data in pixels array.

Description

Constructs a PixelGrabber instance to grab data from the specified area of the image generated by an ImageProducer and store the pixel data from this area in the array pixels[].

Instance Methods

abortGrabbing

public synchronized void abortGrabbing()

Description: Stops the PixelGrabber's image-grabbing process.

getColorModel

public synchronized ColorModel getColorModel()

Returns: The color model the PixelGrabber is using for its array.

getHeight

public synchronized int getHeight()

Returns: The height of the grabbed image, or -1 if the height is not known.

getPixels

public synchronized Object getPixels()

Returns

The array of pixels.

Description

Either a byte array or an integer array is returned, or null if the size and format of the image are not yet known. Because the PixelGrabber may change its mind about what ColorModel it's using, different calls to this method may return different arrays until the image acquisition is complete.

getStatus

public synchronized int getStatus()

Returns: A combination of ImageObserver flags indicating what data is available.

getWidth

public synchronized int getWidth()

Returns: The width of the grabbed image, or -1 if the width is not known.

grabPixels

public boolean grabPixels() throws InterruptedException

Throws

InterruptedException: If image grabbing is interrupted before completion.

Returns

true if the image has completed loading, false if the loading process aborted or an error occurred.

Description

Starts the process of grabbing the pixel data from the source and storing it in the array pixels[] from constructor. Returns when the image is complete, loading aborts, or an error occurs.

public synchronized boolean grabPixels (long ms) throws InterruptedException

Parameters

ms: Milliseconds to wait for completion.

Returns

true if image has completed loading, false if the loading process aborted, or an error or a timeout occurred.

Throws

InterruptedException: If image grabbing is interrupted before completion.

Description

Starts the process of grabbing the pixel data from the source and storing it in the array pixels[] from constructor. Returns when the image is complete, loading aborts, an error occurs, or a timeout occurs.